MIPS: ES6 symbols: Implement Symbol intrinsic and basic functionality

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5766 matching lines @@
     cmp1 = input;
     cmp2 = Operand(JS_FUNCTION_PROXY_TYPE);
     final_branch_condition = eq;
 
   } else if (type_name->Equals(heap()->object_string())) {
     __ JumpIfSmi(input, false_label);
     if (!FLAG_harmony_typeof) {
       __ LoadRoot(at, Heap::kNullValueRootIndex);
       __ Branch(USE_DELAY_SLOT, true_label, eq, at, Operand(input));
     }
-    // input is an object, it is safe to use GetObjectType in the delay slot.
-    __ GetObjectType(input, input, scratch);
-    __ Branch(USE_DELAY_SLOT, false_label,
-              lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
+    if (FLAG_harmony_symbols) {
+      // input is an object, it is safe to use GetObjectType in the delay slot.
+      __ GetObjectType(input, input, scratch);
+      __ Branch(USE_DELAY_SLOT, true_label, eq, scratch, Operand(SYMBOL_TYPE));
+      // Still an object, so the InstanceType can be loaded.
+      __ lbu(scratch, FieldMemOperand(input, Map::kInstanceTypeOffset));
+      __ Branch(USE_DELAY_SLOT, false_label,
+                lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
+    } else {
+      // input is an object, it is safe to use GetObjectType in the delay slot.
+      __ GetObjectType(input, input, scratch);
+      __ Branch(USE_DELAY_SLOT, false_label,
+                lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
+    }
     // Still an object, so the InstanceType can be loaded.
     __ lbu(scratch, FieldMemOperand(input, Map::kInstanceTypeOffset));
     __ Branch(USE_DELAY_SLOT, false_label,
               gt, scratch, Operand(LAST_NONCALLABLE_SPEC_OBJECT_TYPE));
     // Still an object, so the BitField can be loaded.
     // Check for undetectable objects => false.
     __ lbu(at, FieldMemOperand(input, Map::kBitFieldOffset));
     __ And(at, at, 1 << Map::kIsUndetectable);
     cmp1 = at;
     cmp2 = Operand(zero_reg);
@@ skipping 263 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal